Add base and display snippets, initial generation works

src/buttonplus_generator/merger.py

@@ -0,0 +1,20 @@
+from typing import Any, Dict
+
+
+def deep_merge(a: Dict[str, Any], b: Dict[str, Any]) -> Dict[str, Any]:
+    """Recursively merge b into a and return a new dict.
+
+    Lists are concatenated; scalar values in b override a.
+    """
+    result = dict(a)
+    for k, v in b.items():
+        if k in result:
+            if isinstance(result[k], dict) and isinstance(v, dict):
+                result[k] = deep_merge(result[k], v)
+            elif isinstance(result[k], list) and isinstance(v, list):
+                result[k] = result[k] + v
+            else:
+                result[k] = v
+        else:
+            result[k] = v
+    return result